Automatic stride control for artificial legs



Aug. 26, 1952 WALLACE 2,607,923

AUTOMATIC .STRIDE CONTROL FOR ARTIFIQIAL LEGS Filed oct. 30, 1951 ZNTZETE 1 Patented Aug. 26, 1952 UNITED ,STATES PATENT OFFICE AUTOMATIC STRIDE CONTROL FOR ARTIFICIAL LEGS Alfred E. Wallace, West Allis, Wis. Application October 30, 1951, Serial No. 253,843

This invention relates in general toartificial limbs and, in particular, to an artificial leg having a substantially automatic control of the pivoting members of the leg. i

Theindividual who wears a new artificialleg must develop a new walking stride with the leg, and-in doing so it is important that the portion of the leg below the knee, the calf, simulate the normal functioning of that portion of' a real leg by pivoting a relatively small angle (about 30 to '40 degrees) for walking and pivoting a relatively large angle (approximately 90 degrees) when the amputee sits down. However, the members of an artificial leg must always provide a firmsupport for the individual wearing the leg.

The necessity of providing a 90'degree pivot of the lower portion of the leg or calf so that the leg members assume a natural position when the individual sits down makes it diificult to provide a foolproof, natural pivoting artificial leg. Specifically, if while the individual is walking, the calf pivots more than the relatively small angle of the walking stride, the calf will fold under, for a firm support through the pivotal members of the artificial leg is provided only as long as those members are not very far out of axial alignment.

Several knee locks'and controls have been suggested for embodiment in artificial legs. These include pivot limiting devices having a foot or hand control so that under certain circumstances the pivot limiting device-is moved to provide unrestrained pivotal movement ofrthe calf with respect to the thigh.

The attempts to protect the wearer of the leg from the inadvertent collapse of his artificial leg by theprovision of a control or knee lockmust be substantially .automatic and, must be :very simple inconstruction as-there are obvious difiiculties inherent in learning to balance oneself and to walk on an artificial leg, and these diificulties should not be further complicatedby the control provided for the artificial leg. While this is most obviously true where both legs of the individual-are artificial, it is nevertheless also true -in the case of an individual having only one artificial leg, for a person with an artificial leg normally must use both of his hands to brace and support himself and to substantially pull himself from'the seated position to a standin position;v Similarly, the lowering of himself from a walking or standingposition to a seated position is likely to require the strengthoi both hands and arms of the individual. 7

- It is therefore an object of this invention to provide in an artificial leg a control which nors was. (01. 3-2) of the individual requires the restraint mally restrains the relative movement of the leg members to the swing of a natural walking stride and by which the restraint is substantially automatically made inoperative when the wearer sits down, in which position the calf member may pivot a considerable angle to a position of approximately degrees with respect to the thigh. Another object of this invention is to provide an artificial leg which has a restraint to prevent the inadvertent collapse of the leg under the individual while he is walking and which has an automatic, unattended control of the restraint to move it to operative as well as to inoperative positions depending solely upon whether the activity in its operative or inoperative positions. Still another object of this invention is to provide a substantially automatic stride control for artificial legs, and a further object being to provide automatic stride control which is adjustable so that an embodiment of a standard size is adaptable to various sizes of artificial legs. And still another object is to provide an adjustable stride control which is automatically operable completely independent'of any special action on the part of the wearer of the leg.

Still a further object of this invention is to pro.- vide an artificial leg pivot control of very simple construction which is automatically responsive to the normal standing or sitting action of the wearer.

These and other objects and advantages of this invention will become apparent from a consideration of the accompanying drawing, in which:

Figs. 1 to 3, inclusive, are elevation views of a part of an artificial leg embodying this. invention with Figs. 1 and 2 representing the extreme positions of the leg members for the normal walking stride and with Fig. 3 representing the leg in a sitting position. Fig. 4 is a sectional view taken along line IV-IV of Fig. 1. And Fig. 5 is a view in elevation, partly in section, of a modifiedembodiment of an artificial leg with this invention incorporated therein.

This invention may be embodied in any artificial leg which includes a thigh I I havinga knee joint with pivotal means [2 for connecting a calf l 3 to the thigh. V

For the purposes of illustration, a guide is attached to the thigh I I, and in this instance, it is attached to the outer surface of the thigh on a side of the leg with a first end It of the guide attached by a pivot l1 near the rear of the thigh. The guide extends nearly to the front edge of the thigh where the second end 3 of the guide is connected to the thigh by a spring [9. The guide has an arc shape slot 2! which extends from its pivoted end to its spring connected end. A bottom section of the guide is removed so that there is an unobstructed opening 22 into the slot. That opening extends from the spring connected end toward the rear pivoted end a distance more than half the length of the guide. The opening 22 accommodates astop 2S and a first end portion 21 of a lever to which the stop is screw threaded. The stop 28 and end portion 27 substantially fills the opening 22.

Between the end portions of the lever there. is a considerably curved or bent intermediate portion 30 which is attached to the thigh by a pivot 3|, and from which the second endportionlil of the lever extends a spaceddistance to the rear of the posterior outer surface of the thigh. lever is provided with a biasing means such, as the spring 32 which is attached to the lever and to the thigh in order to normally keeping the stop and first end portion of the lever in the opening 22. Spring 32 shown as compressed in Fig. 1, forces the end 29' of thelever 28 away from In this embodiment the calf has .a threaded block 34 into which screws the threaded shaft of .the rod 35, and the position of the rod in the block is secured by nuts 35. Rod 35 extends upwardly from the calf to the uide in the thigh and has a' laterally extending upper end 3'! which is received in the slot 2 I.

In the, modification shown in Fig. the parts are arranged so that'most of the lever and the .And the second end 45 of the lever extends out the posterior of the leg and is normally held a spaced distance to the rear of the posterior outer surface of the calf by the spring biasing means 55. V The function and operation of the control means embodied in artificial legs in accordance with this invention may be understood from a consideration of Figs. 1 to 3 which illustrate the important positions of the leg members. Figs. 1 and 2 show the calf member in its extreme walking positions. When the person wearing the leg is standing upright, the thigh and calf are in substantial axial alignment, and the rod extension from the calf is received in the slotted guide. While in Fig. 1 the lateral end of the extension is at the extreme rear of the slot limiting the calf from pivoting forward of the axial position, the leg also has the conventional abutment of the upper anterior edge 4!) of the calf against the outer anterior surface 39 of the thigh preventing any farther, forward movement of the calf.

When the. wearer of the leg takes a forward step, the calf will pivot at the knee joint and move rearwardly with respect to the thigh. In doing so the end of the rod extension from'the calf will move along the slot'toward the front-of the thigh until it abuts the stop attached to the first end portion of the lever. At that point farther rearwardly, pivoting movement of the calf is impossible as long as the biasing means maintains the stop in the path of the end of the The rod extension, and thereby collapse of the calf while walking is prevented.

However restraint by the stop is substantially automatically overcome when the wearer of the leg sits down. As the posterior of the thigh nears the chair seat 4|, the end portion of the lever which is spaced to the rear of the posterior outer surface of the thigh will abut the seat and be forced forward to the outer surface of the thigh. The lever is so constructed and arranged that this forward movement of the lever pivots the stop out of the path of the rod. The calf is then position.

The predetermined angle of pivot of the calf corresponding to a natural walking stride generally will be approximately thirty to forty degrees which means that the lateral end of the rod will be caused to move along the slot away from the pivoted end of the guide a distance less than'one half the length of the slot before the rod is arrested by the stop. The end of the rod moves on an are which is curved oppositely to the curvature of the slot inthe guide shown in Fig. 1. Therefore, when the calf starts to pivot rearwardly the rod causes the guide to rotate counterclockwise an inch or so about its pivoted end to its position shown in Fig. 2. The amount of rotation depends partly ontne tolerance at the pivoted connection to the guide. This counterclockwise movement of the guide increases the force of the spring connected to the guide so that when the foot of the leg is lifted from the ground the force of the spring somewhat aids in providing a so called kickback of the calf from its rearward pivoted position toward its aligned position. The lever is biased to follow the guide and as the calfmoves from the arrested position. shown. in Fig. 2. to theninety degree position shown in Fig.

3, the guide'returns. toward its position shown in Fig. 1 and causes the lever to rotate slightly clockwise with the guide. At that time the second end 29 of the lever moves forward of the posterior edge of the thigh.

In the modification shown in Fig. 5 the control means is arranged in the calf so the wearer need only abut the posterior of the calf against a chair leg or the front edge of a chair or couch and while holding on to. the arms of the chair or some other support, he can'ease himself onto the seat of the chair or couch. 1

It will be seen that the operation of the vcontrol means is substantially automatic and can therefore be utilized whether the wearer has one or two artificial legs. The control requires no attention whatsoever of the individual, whether he is sitting down or rising to a standing position.

The lever is biased so'that when the wearer has pulled himself only part way to the "standing position and the end of the rod has moved back out of the opening in the guide, the calf will automatically be stopped from collapsing just as the operation of the control means was substantially automatic when the wearer sat down. As previously mentioned the end of the lever and the stop attached to it extend substantially. the length .of the opening in the guide; therefore,

the lateral end of the rod cannot become caught behind the end of the lever and thereby that end of the rod cannotbe prevented from automatically returning to the rear portion of the slot when the individual rises from a sitting position.- I In order to easily adaptthis invention to artificial legs the stop is screw threaded into the end '5 portion of the lever s'othat the angle of pivot of the calf may be adjusted to a predetermined angle corresponding to 'a normal walking stride of the wearer.-' This'is especially important in that it may not be possible to accurately determine-the correct maximum angle the calf should be permitted to pivot for the walking stride of the particular wearer until after the wearer has become proficient in the use of the artificial leg. Also, to make a standard control means adaptable to a large number of artificial legs the shaft of the rod extension is adjustably extendible from the calf. f In this instance, this is accom lished by threading the shaftof thee'xtension and screwing it into the calf. j

Although the invention has been described in relation to certain'specific embodiments, changes or modifications thereof are possible without. departing, from the scope of the invention. It is intended that the abovedescription and the accompanying drawing should be considered as only illustrative .The inventionis defined by the SCOp'e of the appended claims.

I It is claimed and desired to secure as Letters Patent: j 1 An artificial leg comprising aflfirst and a second member, pivotal means connecting said members together, at" a .knee joint, and control means including an extension fromsaid second member, a stop attached to said first member and normally positioned in the path of said extension to'arrest the movement of said extension limiting the relative'movement of said members to a predetermined angle, a lever for moving said tstop into mom of the path of said extension, said lever. having a first and secondend portions and an intermediate portion, said first end portion including said stop, said intermediate portion pivotably connectedto saidfirst member, said second ,end' portion being outside first member spaced from. the-outer surfacethereof, movement of said second-end portion to the outer surface of said firstmember pivoting said stop out of. the path of said extension, and biasing means normally forcing-said stop into thepath" ofsaid tioned in the path of said rod to arrest the movement of said rod limiting the relative movement of said members to a predetermined angle, a lever for moving said stop into or out of the path of said rod, said lever having first and second end portions and an intermediate portion, said first end portion including said stop, said intermediate portion pivotably connected to said calf member, said second end portion being outside said calf member spaced from the outer posterior surface thereof, movement of said second end portion to the outer posterior surface of said calf member pivoting said stop out of the path of said rod, and biasing means normally forcing said stop into the path of said rod and forcing said second end portion to its normal position spaced from the outer surface of said calf member.

3. An artificial leg comprising a thigh member and a calf member, pivotal means connecting said members together at a knee joint, and con- 6 trol means including a slottedguide in said calf member, a rod fixed to said thigh'member and extending from said thigh into said slotted guide, pivotal movement of said members causing said rod to be moved in said slotted guide, a stop normally positioned in the path of said rodjto' arrest the movement of said members 'to'a pre-- determined angle, a lever for moving said-stop into or out of the path of said 'rod, said'leve'r having first and second endportions and' an intermediate portion, said first end portionfin cluding said stop, said intermediate portion pivotably connected to said calf member, said second end portion being outside the posterior of said calf member and spaced from the 'o'uter surface thereof, movement of said second'end portion to the outer surface of said calf 'mem ber pivoting said stop out of the path of said rod, and biasing means normally forcing said stop into the path of said rod and forcingsaid second end portion to its normal position spaced from the outer surface of said calf member. i 4. An artificial leg comprising a first and'a second: member, pivotal means connecting said members together at a knee joint, and control means including a slotted guide in said first member, a rod fixed to said second member and extending from said second member into said slotted guide, pivotal movement of said members causing said rod to move along said guide, a stop normally positioned in the path of said rod to arrest the movement of said rod limiting the relative movement of said members to" apre determined angle, a lever for substantially auto matica'lly moving said stop into or out o f'f the path of said rod, said lever having first and second end portions, said first end portion includ ing said stop, said lever pivotably connected to said first member, said second end portion normally being outside said first member and'spaced from the outer surface thereof, movement of said second end portion to the outer surface of said first member pivoting said stop out'of 'the 'pa'th ofsaid rod, and a biasing means normally'fo'r'cing said stop into the path of said rod and forefing said second end portion to its' said normal position spaced from the outer surface" of said first member.

second member, pivotal means connectingsaid member together at a knee joint, anaconda means including a guide attached tosaid first member, said guide, having a slot, a rod'fixed to said second member and extending from? said second-member to said guide, said rodhaving a lateral end received'in said slot; pivotal-movement of said members causing said lateral end to move along said slot, a stop spaced along said slot and normally positioned in the path of said lateral end to arrest the movement of said lateral end limiting the relative movement of said members to a predetermined angle, a lever for substantially automatically moving said stop into or out of the path of said lateral end, said lever having first and second end portions and an intermediate portion, said first end portion including said stop, said intermediate portion pivotably connected to said first member, said second end portion being outside said first member and spaced from the outer surface thereof, movement of said second end portion to the outer surface of said first member pivoting said stop out of the path of said lateral end and forcing said second end portion to its normal position spaced from the outer surface of said first member.

arom s 7 6-, An artificial leg comprising first and second members, pivotal means connecting said members together at a knee joint, and control means including a guide, a pivot connection between a first end of said guide and said first member, a spring connection between the "second end of said guide and said first member, said guide having an are shaped slot, a rod fixed-to said second member and extending from said second member to said guide, said rod having a lateral end re ceived in said slot, said lateral end being adjacent said first end of said guide when said first and second members are in substantial axial 'alignment, pivotal movement of said-members causing said lateral end to move alongsaid slot away from said first end of said guide and causing said guide to rotate slightly about its pivoted end increasing the spring force tending to return said guide and rod to their respective relative positions representing axial alignment of said meme bers, a stop spaced along said slot and normally positioned in the path of said lateral end to arrest the movement of said lateral end limiting the relative movement of said members to a predetermined angle, said rod being adjustably extendible from said second member and said stop being adjustable with respect to its position in said slot to provide adjustment of said predetermined angle, a lever for substantially automatically moving said stop into or out of the path of said lateral end, said lever having first and second end portions and an intermediate, portion, said first end portion including said-stop, said intermediate portion pivotably connected to said first member, said second end portion being outside said first member spaced to the rear of the outer posterior surface thereof, said, lever being so constructed and arranged whereby movement of said second end portion to the outer surface of said first member pivots said stop into or out of hepathof said rodgsaid lever having first and-second end portions and an intermediate portion, said first end portion including said stop and being movable to aposition in saidslot, said intermediate portion pivotably connectedtosaid calf member, said second end portion being outside the posterior of said'calf member and spaced from the outer posteriorsurface thereof, movement of said second end portion to the outer posterior surface of said calf member pivoting said stop out; of the'path of said rod whereby said calf member can be moved without restraint beyond said predetermined angle through anadditional angle, said first end portion and saidstop extending a length along, said slot at distance substantially corresponding to the distance defined in said slot byv said additional, angle whereby said first end portion and said stop are prevented from moving to said position while said rod is within said additional angle, and biasing means normally forcing said first end portion and said stopinto said position in the ,path of said rod and forcing said second. end portion to its normal position spaced from the outer posterior surface of said calf member.

8. An artificial leg comprising a first and a second member, pivotal means connecting said members together at knee joint, and control means including a, slotted guide in said second member, a rod fixed to said first member and extending; from said first member into said slotted guide, pivotal movement of said members causing said rod to be moved in said slotted guide, a stop normally positioned in the path of said rod to arrest the rearward movement of said second member to a predetermined angle, a lever for moving said stop into or out of the path of said rod, said lever pivotably connected stop-out of the path of said lateral end, and

a '7. An artificial leg comprising thigh member and a calf member, pivotal means connecting said members together at a knee joint, and control means including a slotted guide in said calf member, a rod fixed to said thigh member and extendingrfrom said thigh into said slotted guide,

pivotal movement of members causing said rod to be moved in said slotted guide, a stop normally positioned in the path of said rod to arrest the rearward movement of said calf member-to a predetermined angle, a lever for moving said to said second member and having an end portion spaced to the rear of the posterior of said second member, movement of said end portion to the outer posterior surface of said second member pivoting said stop outof the path ofsaid rod whereby said second member can be moved without restraint beyond said predetermined angle through an additional angle, said stop being adjustable in said first end portion to change said predetermined angle, and biasing means normally forcing said stop into said position in the path of said rod and forcing said end portion to its normal position spaced from the outer posterior surface of said second mem- {No references cited. 

